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DEHRADUN INSTITUTE OF TECHNOLOGY DEPARTMENT OF ELECTRICAL ENGINEERING
UTILIZATION OF ELECTRICAL ENERGY & ELECTRIC TRACTION TRAIN MOVEMENT AND ENERGY CONSUMPTION
http://eedofdit.weebly.com Prepared By: Mohamed Samir
Types of Railway Services – There are three types of passenger services which traction
system has to cater for – namely Urban, Sub-urban and Main line services.
1. Urban or city service – In this type of service there are frequent stops, the distance
between stops being nearly 1 km or less. Thus in order to achieve moderately high
schedule speed between the stations it is essential to have high acceleration and
retardation.
2. Sub-urban service – In this type of service the distance between stops averages from
3 to 5 km over a distance of 25 to 30 km from the city terminus. In this case also,
high rates of acceleration and retardation are necessary.
3. Main line service – In this type of service the distance between stations is long. The
stops are infrequent and hence the operating speed is high and periods
corresponding to acceleration and retardation are relatively less important.
The characteristics of each type of service are given in table 1 given below:
S.No. Parameter of Comparison Urban Service Sub – urban
Service Main line Service
1 Acceleration 1.5 to 4 kmphps 1.5 to 4 kmphps 0.6 to 0.8 kmphps
2 Retardation 3 to 4 kmphps 3 to 4 kmphps 1.5 kmphps
3 Maximum Speed 120 kmph 120 kmph 160 kmph
4 Distance between
stations 1 km 2.5 to 3.5 km More than 10 km
5 Special Remark Free running
period is absent
and coasting
period is small
Free running period
is absent and
coasting period is
long
Long free running
and coasting
periods.
Acceleration and
braking periods
are comparatively
small
Speed Time Curves for Train Movement - The movement of trains and their energy
consumption can be conveniently studied by means of speed-time and speed-distance
curves. The speed time curve is the curve showing instantaneous speed of train in kmph
along ordinate and time in seconds along abscissa. The area in between the curve and
abscissa gives the distance travelled during given time interval. The slope of the curve at any
point gives the value of acceleration or retardation. The fig. 1 shows a typical speed time
curve for electric trains operating on passenger services. It mainly consists of (i) constant
acceleration period, (ii) acceleration on speed curve, (iii) free running period, (iv) coasting
period and (v) braking period
(i) Constant Acceleration Period (0 to t1) – During this period the traction motors
accelerate from rest, the current taken by the motors and the tractive effort are
practically constant. It is also known as notching up period and it is represented by
portion OL of the speed time curve.
(ii) Acceleration on Speed Curve (t1 to t2) – After the starting operation of the motors is
over, the train still continues to accelerate along the curve LM. During this period,
DEHRADUN INSTITUTE OF TECHNOLOGY DEPARTMENT OF ELECTRICAL ENGINEERING
UTILIZATION OF ELECTRICAL ENERGY & ELECTRIC TRACTION TRAIN MOVEMENT AND ENERGY CONSUMPTION
http://eedofdit.weebly.com Prepared By: Mohamed Samir
the motor current and torque decrease as train speed increases. Hence, acceleration
gradually decreases till torque developed by the motors exactly balances that due to
resistance to the train motion. The shape of LM portion of the speed time curve
depends primarily on the torque speed characteristics of the traction motors.
(iii) Free Running Period (t2 to t3) – At the end of speed curve running i.e. at t2 the train
attains the maximum speed. During this period the train runs at constant speed
attained at t2 and constant power is drawn. This period is represented by the portion
MN of the speed time curve.
(iv) Coasting Period (t3 to t4) – At the end of free running period (i.e. at t3) the power
supply is cut off and the train is allowed to run under its own momentum. The speed
of the train starts decreasing due to the resistance offered to the motion of the train.
The rate of decrease of speed during coasting period is known as coasting
retardation (which practically remains constant). Coasting is desirable because it
utilizes some of the kinetic energy of the train which would otherwise, be wasted
during braking. This helps in reducing the energy consumption of the train. The
coasting period is represented by the portion NP of the speed time curve.
(v) Braking Period (t4 to t5) – During this period brakes are applied and the train is
brought to a stop. This is represented by the portion PO of the speed time curve.
Fig. 1 Actual Speed Time Curve of Train
Simplified Speed Time Curve - The actual speed time makes calculations quite difficult as
some part of it is non – linear. Therefore in order to make calculations simpler with least
error the speed time curve is modified by keeping both the acceleration and retardation as
well as distance between stations the same for both actual and modified speed time curves.
The speed time curves are modified in two ways – (a) Trapezoidal speed time curve and (b)
Quadilateral speed time curve as shown in fig. 2 In the case of simplified trapezoidal speed
time curve OA’B’C speed curve running and coasting periods are replaced by constant speed
period. On the other hand, in case of simplified quadrilateral speed time curve OA”B”C ,
speed curve running and coasting periods are extended. The trapezoidal speed time curve
gives closer approximation of the conditions of main line service where long distances are
involved and quadrilateral speed time curve is suitable for urban and sub-urban services.
Time (in seconds)
Sp
ee
d (
km
ph
)
O t1 t2 t3 t4 t5
L
M N
O
P
Braking
Coasting
Free running Acceleration on
speed curve
Rheostatic
acceleration
DEHRADUN INSTITUTE OF TECHNOLOGY DEPARTMENT OF ELECTRICAL ENGINEERING
UTILIZATION OF ELECTRICAL ENERGY & ELECTRIC TRACTION TRAIN MOVEMENT AND ENERGY CONSUMPTION
http://eedofdit.weebly.com Prepared By: Mohamed Samir
Fig.2 Simplified Speed Time Curve
Trapezoidal Speed Time Curve - The fig.3 shows a simplified trapezoidal speed time curve
with speed in kmph and time in seconds. If Vm is the maximum speed attained, α is
acceleration in kmphps and β is retardation in kmphps; D is the total distance travelled in
km then
Fig.3 Simplified Trapezoidal Speed Time Curve
Time of acceleration t1 = αmV seconds
Time of retardation t2 = βmV seconds
If T is the total time of travel then T = t1 + t2 + t3
Total distance of travel D = area OABC = area OAD + area ABED + area BEC
( )
××+×+
××= ECBEABADODADD2
1
2
1
[ ]321
321 2720036002
1
360036002
1ttt
VtV
tV
tVD m
mmm ++=
××+
×+
××=
Time
Sp
ee
d
A
A’
A”
B
B’
B”
A B
t1
Time
Sp
ee
d
t2 t3
Vm
O C D E
DEHRADUN INSTITUTE OF TECHNOLOGY DEPARTMENT OF ELECTRICAL ENGINEERING
UTILIZATION OF ELECTRICAL ENERGY & ELECTRIC TRACTION TRAIN MOVEMENT AND ENERGY CONSUMPTION
http://eedofdit.weebly.com Prepared By: Mohamed Samir
[ ] [ ]
−−=−−=+−−+=βαmmmmm VV
TV
ttTV
tttTtV
D 27200
27200
)(27200
313311
+−=βα11
27200
mm VT
VDor
If αββα
2
+=K then [ ] [ ]KVT
VKVT
VD m
mm
m −=−=3600
227200
K
KDTTVorDTVKVor mmm
2
1440003600
22 −±
==+−
The positive sign gives a very high value of Vm which is not possible in practice. Hence
negative sign is considered for calculating the value of maximum speed of train.
Hence K
KDTTVm
2
144002 −−
=
Quadrilateral Speed Time Curve – The fig.4 shows the simplified quadrilateral speed time
curve with speed in kmph and time in seconds. If α = acceleration in kmphps, βC = coasting
retardation in kmphps, β = braking retardation in kmphps, V1 = maximum speed at the end
of acceleration in kmph, V2 = speed at the end of coasting in kmph, T = total time of run in
seconds then
Fig.4 Simplified Quadrilateral Speed Time Curve
Time of acceleration t1 = α
1V seconds
Time of coasting retardation t2 = C
VV
β21 − seconds
Time of braking retardation t3 = β
2Vseconds
Total distance of travel D = area OABC = area OAD + area ABED + area BEC
( )
××+
×++
××= ECBEDEBEADODADD2
1
2
1
2
1
t1 t2 t3
Time
O C D E
A
B
Sp
ee
d
V1
V2
DEHRADUN INSTITUTE OF TECHNOLOGY DEPARTMENT OF ELECTRICAL ENGINEERING
UTILIZATION OF ELECTRICAL ENERGY & ELECTRIC TRACTION TRAIN MOVEMENT AND ENERGY CONSUMPTION
http://eedofdit.weebly.com Prepared By: Mohamed Samir
( )
××+
×++
××=36002
1
36002
1
36002
1 32
221
11
tV
tVV
tVD
( ) ( )32
221
132222111
720072007200720072007200tt
Vtt
VtVtVtVtVD +++=
+++=
( ) ( )1
23
1
72007200tT
VtT
VDor −+−= since T = t1 + t2 + t3
( )1231211223117200 tVtVVVTtVTVtVTVDor −−+=−+−=
αβ1
22
121 )(7200V
VV
VVVTDor ×−×−+=
)1(11
)(7200 2121 −−−−
+−+=βα
VVVVTD
Also V2 = V1 – βCt2 = V1 – βC(T – t1 – t3) =
−−−βα
β 211
VVTV C
−−=
−
αβ
ββ
1122
VTVVVor C
C
)2(
1
11
2 −−−−
−
+−=
ββ
αβ
β
C
CC VTV
Vor
Solving equation (1) and equation (2) we can determine the values of D, V1, V2 etc.
Speed Time Curves for Railway Services – The fig.5 (a) and fig.5 (b) shows the typical speed
time curves for urban, suburban and main line railway services. There is no free running
period both in the case of urban and suburban railway services. In case of suburban services
the coasting period is longer than coasting period of urban service. Hence the simplified
quadrilateral speed time curve is most suited for calculations regarding urban and suburban
services. In the case of main line services, the free running period is the longest period and
acceleration, coasting and retardation periods are comparatively smaller. The coasting
period can be neglected in the case of main line services and hence the simplified
trapezoidal speed time curve is most suited for calculations.
Fig.5 (a) Speed Time Curves for Urban and Sub-Urban Services
DEHRADUN INSTITUTE OF TECHNOLOGY DEPARTMENT OF ELECTRICAL ENGINEERING
UTILIZATION OF ELECTRICAL ENERGY & ELECTRIC TRACTION TRAIN MOVEMENT AND ENERGY CONSUMPTION
http://eedofdit.weebly.com Prepared By: Mohamed Samir
Fig.5 (b) Speed Time Curves for Main line Services
Crest Speed – It is the maximum speed (Vm) attained by the vehicle during the run.
Average Speed - It is defined as the ratio of the distance covered between two stops and
the actual time of run.
kmphT
DVSpeedAverage a 3600×=
Where D = distance between the stops in km and T = actual time of run in seconds
Schedule Speed – It is defined as the ratio of the distance covered between two stops and
total time of run including the time of stop.
( ) kmphtT
DVSpeedSchedule
S
S 3600×+
=
Where D = distance between the stops in km, T = actual time of run in seconds and tS = time
of stop in seconds.
The schedule speed is always smaller than average speed. The difference is large in case of
urban and suburban services whereas negligibly small in case of main line service. In case of
urban and suburban services the stops must be reduced to have a fairly good schedule
speed.
Factors Affecting Schedule Speed – The schedule speed of a train when running on a given
service (i.e. with a given distance between the stations) depends upon the following factors:
• Acceleration and braking retardation
• Maximum or crest speed
• Duration of stop
(a) Effect of Acceleration and Braking Retardation – For a given run and with fixed crest
speed the increase in acceleration will result in decrease in actual time of run and
lead to increase in schedule speed. Similarly increase in braking retardation will
affect speed. The variation in acceleration and retardation will have more effect on
schedule speed in case of shorter distance run in comparison to longer distance run.
(b) Effect of Maximum Speed – With fixed acceleration and retardation, for a constant
distance run, the actual time of run will decrease and therefore schedule speed will
DEHRADUN INSTITUTE OF TECHNOLOGY DEPARTMENT OF ELECTRICAL ENGINEERING
UTILIZATION OF ELECTRICAL ENERGY & ELECTRIC TRACTION TRAIN MOVEMENT AND ENERGY CONSUMPTION
http://eedofdit.weebly.com Prepared By: Mohamed Samir
increase with increase in crest speed. In case of long distance run, the effect of
variation in crest speed on schedule speed is considerable.
(c) Duration of Stop – The schedule speed for a given average speed will increase by
reducing the duration of stop. The variation in duration of stop will affect the
schedule speed more in case of shorter distance run in comparison to longer
distance run.
Mechanism of Train Movement – The fig. 6 shows the essentials of driving mechanism in an
electric vehicle. The armature of the driving motor has a pinion of diameter d’ attached to it.
The tractive effort at the edge of the pinion is transferred to the driving wheel by means of a
gear wheel.
Fig.6 Essentials of driving mechanism in an electric vehicle
Let the driving motor exert a torque T in Nm, d = diameter of the gear wheel in meters, d’ =
diameter of pinion of motor in meters, D = diameter of driving wheel in meters, γ = gear
ratio η = efficiency of transmission.
The tractive effort at the edge of the pinion is given by the equation
'
2'
2
''
d
TFor
dFT ==
Tractive effort transferred to the driving wheel is given by the equation
DT
d
d
DT
D
dFF
γηηη
2
'
2' =
=
=
The maximum frictional force between the driving wheel and the track = µW where µ is the
coefficient of adhesion between the driving wheel and the track and W is the weight of the
train on the driving axles (called adhesive weight). Slipping will not take place unless tractive
effort F > µW. For motion of trains without slipping tractive effort F should be less than or at
the most equal to µW but in no case greater than µW.
The magnitude of the tractive effort that is required for the movement of vehicle
depends upon the weight coming over the driving wheels and the coefficient of adhesion
F’
F
Armature of Traction Motor
Pinion of Motor
Gear Wheel
Road Wheel
DEHRADUN INSTITUTE OF TECHNOLOGY DEPARTMENT OF ELECTRICAL ENGINEERING
UTILIZATION OF ELECTRICAL ENERGY & ELECTRIC TRACTION TRAIN MOVEMENT AND ENERGY CONSUMPTION
http://eedofdit.weebly.com Prepared By: Mohamed Samir
between the driving wheel and the track. The coefficient of adhesion is defined as the ratio
of tractive effort to slip the wheels and adhesive weight.
i.e. coefficient of adhesion a
t
W
F
weightadhesive
wheelsthesliptoefforttractive==µ
The normal value of coefficient of adhesion with clean dry rails is 0.25 and with wet or
greasy rails the value may be as low as 0.08. It depends upon the following factors:
• Coefficient of friction between wheels and the rail.
• Nature of motor speed – torque characteristics – a characteristic with low speed
regulation is preferred.
• Series – parallel connections of motors.
• Smoothness with which the torque can be controlled.
• Speed of response of the drive.
Driving Axle code for Locomotives – The weight of a locomotive is supported on axles which
are coupled to the wheels. The weight per axle is limited by the strength of the track and
bridges, and usually varies between 15 and 30 tonnes. The total number of axles is
calculated by the following equation:
AxleperweightePermissibl
LocomotiveofWeightAxlesofNumber =
The number of driving axles and coupled motors are described using a code as follows:
2 driving axles ---- Category B
3 driving axles ---- Category C
4 driving axles ---- Category BB
6 driving axles ---- Category CC
When each axle is driven by an individual motor, a subscript ‘O’ is used alongwith these
symbols. When axles are divided into groups and each group is driven by single motor, only
letters B and C are appropriately used. The number of dummy (non-driving) axles is denoted
by numerals.
Tractive Effort for Propulsion of Train – The effective force necessary to propel the train at
the wheels of locomotive is called the tractive effort. It is tangential to the driving wheels
and measured in newtons.
Total tractive effort required to run a train on track = Tractive effort required for linear and
angular acceleration + Tractive effort to overcome the effect of gravity + Tractive effort to
overcome the train resistance
Or Ft = Fa ± Fg + Fr
(i) Tractive Effort for Acceleration – The force required to accelerate the motion of the body
according to the laws of dynamics is given by the expression
Force = Mass X Acceleration
Let us consider a train of weight W tonnes being accelerated at α kmphps
Mass of train m = 1000 W kg
Acceleration = α kmphps = α X 2
3600
1000sm = 0.2778 α 2sm
DEHRADUN INSTITUTE OF TECHNOLOGY DEPARTMENT OF ELECTRICAL ENGINEERING
UTILIZATION OF ELECTRICAL ENERGY & ELECTRIC TRACTION TRAIN MOVEMENT AND ENERGY CONSUMPTION
http://eedofdit.weebly.com Prepared By: Mohamed Samir
Tractive effort required for linear acceleration is given by
Fa = m α = 1000 W x 0.2778 α = 277.8 Wα N
When a train is moving then the rotating parts of the train such as wheels and motors
also accelerate in an angular direction and therefore the tractive effort required is equal
to the arithmetic sum of tractive effort required to have angular acceleration of rotating
parts and tractive effort required to have linear acceleration. Hence while calculating
tractive effort for acceleration, We (equivalent or accelerating weight of train) is
considered which is generally higher than the dead weight W by 8 to 15 percent. Hence
the net tractive effort required for acceleration is given by
NewtonsWF ea α8.277=
(ii) Tractive Effort for Overcoming the Effect of Gravity – When a train is on a slope, a force
of gravity equal to the component of the dead weight along the slope acts on the train
and tends to cause its motion down the gradient or slope.
Fig.7 Gradient of Railway Track
From fig. 7 we have force due to gradient Fg = 1000W sin θ ---- (1)
In railway work gradient is expressed as rise in meters in a track distance of 100 meters
and is denoted as percentage gradient (G%)
G = sin θ x 100 or sin θ = G/100. Substituting the value of sin θ in equation (1) we get
8.91010100
1000 ×==×= WGkgWGG
WFg
NewtonsWGFg 98=
When a train is going up a gradient, the tractive effort will be required to balance this
force due to gradient but while going down the gradient, the force will add to the tractive
effort.
(iii) Tractive Effort for Overcoming the Train Resistance – The train resistance consists of all
the forces resisting the motion of the train when it is running at uniform speed on a
straight and level track. Under these circumstances the whole of the energy output from
the driving axles is used against train resistance. The train resistance consists of the
following:
a) Mechanical Resistance – It consists of internal resistance like friction at axles,
guides, buffers etc and external resistance like friction between wheels and rail,
DEHRADUN INSTITUTE OF TECHNOLOGY DEPARTMENT OF ELECTRICAL ENGINEERING
UTILIZATION OF ELECTRICAL ENERGY & ELECTRIC TRACTION TRAIN MOVEMENT AND ENERGY CONSUMPTION
http://eedofdit.weebly.com Prepared By: Mohamed Samir
flange friction etc. The mechanical resistance is almost independent of train speed
but depends upon its dead weight.
b) Wind Resistance – It varies directly as the square of the train speed.
The train resistance depends upon various factors, such as shape, size and condition of track
etc. and is expressed in newtons per tonne of the dead weight. For a normal train the value
of specific resistance has been 40 to 70 N/t. The general equation for train resistance is
given as 2
321 VkVkkr ++=
Where k1, k2 and k3 are constants depending upon the train and the track etc., r is train
resistance in N/t and V is speed in kmph. The first two terms represent the mechanical
resistance and the last term represents wind resistance.
The tractive effort required to overcome the train resistance is given by
NewtonsrWFr ×=
The total tractive effort required by a train is given by the following equation
newtonsWrWGWFFFF ergat +±=+±= 988.277 α
+ve sign is taken for the motion up the gradient
- ve sign in taken for the motion down the gradient
Power Output From Driving Axles – The power output is given by
vFvelocityeffortTractivetime
cediseffortTractiveworkdoingofRateP t ×=×=
×==
tan
Where Ft is the tractive effort and v is the train velocity
When Ft is in newton and v is in m/s then P = Ft x v watt
When Ft is in newton and v is in kmph, then we have kWv
Fwattv
FP tt
×=
××=
36003600
1000
If η is the efficiency of transmission gear, then power output of motors
kmphinvkWvF
PandsminvwattvF
P tt ...3600
/...ηη
×=
×=
Energy Output From Driving Axles – Energy is defined as capacity to do work is given by the
product of power and time.
Fig.8
A B
t1
Time
Sp
ee
d
t2 t3
Vm
O C D E
DEHRADUN INSTITUTE OF TECHNOLOGY DEPARTMENT OF ELECTRICAL ENGINEERING
UTILIZATION OF ELECTRICAL ENERGY & ELECTRIC TRACTION TRAIN MOVEMENT AND ENERGY CONSUMPTION
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( ) ( ) DFtvFtvFE ttt ×=××=××=
where D is the distance travelled in the direction of tractive effort. The total energy output
from driving axles for the run is given by
E = Energy during acceleration + Energy during free run
From fig.8 we have ABEDareaFOADareaFE tt ×+×= '
2
'
12
1tVFtVFEor mtmt ×+×=
Where Ft = the tractive effort during acceleration periods
And Ft’ = 98 MG + Mr provided there is an ascending gradient
Specific Energy Consumption – The specific energy output is the energy output of the
driving wheel expressed in watt-hour (Wh) per tonne-km (t-km) of the train. It can be found
by first converting the energy output into Wh and then dividing it by the mass of the train in
tonne and route distance in km. Hence, unit of specific energy output generally used in
railway is Wh/tonne-km (Wh/t-km). The specific energy output is used for comparing the
dynamical performances of trains operating to different schedules.
While calculating the specific energy output, the total energy output of driving wheels is
calculated and then it is divided by the train mass in tonne and route length in km. It is
assumed that there is a gradient of G throughout the run and power remains ON upto the
end of free run in case of trapezoidal curve and upto the accelerating period in case of
quadrilateral curve. The output of the driving axles is used for accelerating the train,
overcoming the gradient and overcoming the train resistance.
Fig.9 Trapezoidal Speed Time Curve
(i) Energy required to accelerate the train (Ea) – From fig.9 corresponding to the
trapezoidal speed time curve we have
Ea = Fa x distance OAD
ααα m
memea
VVMtVME ××=×=
2
18.277
2
18.277 1
αα mm
ea
VVME ×
×××=
3600
1000
2
18.277
A B
t1
Time
Sp
ee
d
t2 t3
Vm
O C D E
DEHRADUN INSTITUTE OF TECHNOLOGY DEPARTMENT OF ELECTRICAL ENGINEERING
UTILIZATION OF ELECTRICAL ENERGY & ELECTRIC TRACTION TRAIN MOVEMENT AND ENERGY CONSUMPTION
http://eedofdit.weebly.com Prepared By: Mohamed Samir
It may be noted that since Vm is in kmph, it has been converted into m/s by multiplying it
by conversion factor of (1000/3600). In case of Vm. In case of Vm/α conversion factor for
Vm and α being same cancel out each other. Since 1 Wh = 3600 J therefore
WhVV
ME mmea
3600
1]
3600
1000
2
1[8.277 ××
×××=
αα
WhMVEor ema
201072.0=
(ii) Energy required overcoming gradient (Eg) – In this case we consider the distance
travelled for the period over which the power remains ON. The energy required to
overcome gradient is given by
Eg = Fg x D’ where D’ is the total distance over which the power remains ON. Its maximum
value equals the distance represented by area DABE in fig. 9 i.e. from the start to the end of
free running period in case of trapezoidal curve
( ) kminisDwhereMGDJoulesDMGEg
''' 98000100098 ==
WhMGDWhMGDEor g
'' 25.273600
198000 =×=
(iii) Energy required to overcome resistance (Er) – The energy required to overcome the
train resistance is given by
( ) JoulesDrMDFE rr
'' 1000. ×=×=
WhMrDWhDrM
Eor r
''
2778.03600
1000.=
×=
Total energy output of the driving axles is given by rga EEEE ++=
( )WhMrDMGDMVE em
''2 2778.025.2701072.0 ++=
lengthruntotaltheisDwhereDM
EEOutputEnergySpecific spo ×
=
kmtWhD
Dr
D
DG
M
M
D
VEor em
spo −
++•= /2778.025.2701072.0
''2
------(1)
If there is no gradient then
kmtWhD
Dr
M
M
D
VEor em
spo −
+•= /2778.001072.0
'2
Factors Affecting Specific Energy Consumption – The factors which affect the specific
energy consumption of an electric train operating on a given schedule speed are as follows:
(a) Distance between the stops
(b) Acceleration
(c) Retardation
(d) Maximum speed
(e) Nature of route
(f) Type of train equipment
The specific energy output is independent of locomotive overall efficiency. From equation
(1) it can be seen that specific energy consumption depends upon the maximum speed Vm,
the distance travelled by the train while power is ON, the specific resistance r , gradient G
DEHRADUN INSTITUTE OF TECHNOLOGY DEPARTMENT OF ELECTRICAL ENGINEERING
UTILIZATION OF ELECTRICAL ENERGY & ELECTRIC TRACTION TRAIN MOVEMENT AND ENERGY CONSUMPTION
http://eedofdit.weebly.com Prepared By: Mohamed Samir
and distance between stops. Therefore greater the distance between stops lesser will be the
specific energy consumption. For a given run at a given schedule speed, greater the value of
acceleration and retardation , more will be the period of coasting and therefore lesser the
period during which power is ON and therefore specific energy consumption will be less.
Steep gradient will involve more energy consumption even if regenerative braking is used.
Similarly more the train resistance, greater will be the specific energy consumption. The
typical values of specific energy consumption are 50 – 75 watt-hours per tonne-km for
suburban services and 20 – 30 watt-hours per tonne-km for main line service.
Dead weight – It is defined as the total weight of locomotive and train to be pulled by the
locomotive
Accelerating weight – It is the dead weight of the train which is divided into two parts –
(i) the weight which requires angular acceleration such as weight of wheels, axles, gears etc.
and (ii) the weight which requires linear acceleration. The effective weight which is greater
than dead weight is called the accelerating weight and it is taken as 5 to 10 percent more
than the dead weight.
Adhesive weight – The total weight to be carried on the driving wheels is known as the
adhesive weight.
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